Thermodynamic modeling of nickel and iron reduction from B₂O₃ – CaO – Fe₂O₃ – NiO melt by СО – СО₂ and Н₂ – Н₂О mixtures

To predict the conditions for metals reduction from an oxide melt by gas in bubbling processes, a thermodynamic modeling technique has been developed that provides an approximation to real systems. The main difference between the accepted method and the well-known one is in conducting successive calculation cycles with withdrawal of the generated gases and the metal phase from the working medium. This paper presents the results of thermodynamic modeling of nickel and iron reduction processes from B₂O₃ – CaO– Fe₂O₃ – NiO melts by mixtures of CO– CO₂ and H₂ – H₂O containing 0 – 60 % CO₂ (H₂O) in the temperature range of 1273 – 1673 K. The calculations evaluated the content of nickel and iron oxides in the melt and the degree of their reduction. It is shown that, regardless of the gas composition, this process proceeds in several stages. At the first stage, Fe₂O₃ is reduced to Fe₃O₄ and FeO. С_Fe2O3 values decrease to almost zero, while С_Fe3O4 and C_FeO increase simultaneously. By the end of the phase, С_FeO reaches its maximum value. At the second stage, the Fe₃O₄ → FeO transition occurs, when С_Fe3O4 values reach maximum, nickel and iron begin to reduce to metal. At reduction by CO– CO₂ mixture, an increase in temperature reduces the metallization of both nickel and iron. Similarly, an increase in the CO₂ content of the introduced gas affects. During interaction of the oxide melt with a gas containing 60 % CO₂ , the third stage is absent. At reduction by H₂ – H₂O mixture, an increase in temperature reduces the metallization of nickel, but increases metallization of iron. With increasing water vapor content in the introduced gas, the degree of metallization of both nickel and iron decreases. The obtained data are useful for creating technologies for selective reduction of metals and formation of ferronickel of the required composition.

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